A projection of the 2017 election
I did a lot of work before the 2015 election trying to anticipate what might happen seat by seat in that election, looking at local factors, candidates, demographics, recent local election results, Lord Ashcroft‘s constituency opinion polling and all of that. Like most prediction efforts in 2015, it was not very successful. It was swamped by three things – (1) the broad national tide in England and Wales that submerged quite a lot of the local differences I anticipated. Part of the Conservative success was built on ‘nationalising’ the election choice, to the detriment of the Lib Dems in particular who were hoping for personal votes to salvage them as happened in elections when their tide has been receding, such as 1979. (2) the completeness of the SNP sweep in Scotland. (3) the extraordinary success of the Conservatives with their protective targeting of the marginals they gained in 2010 and a handful of Labour seats they picked off. I’ve tried out a different approach this time, with a mechanistic formula applied to all the English and Welsh Con/ Lab seats and nowhere else. Martin Baxter at Electoral Calculus has done a vastly more sophisticated and complete version of the same sort of exercise, but this is a crude formula incorporating rather few variables. It’s based on the swing to the Conservatives being partly proportional to the UKIP vote, an element of uniform national swing, a bump in one direction or another for seats at the outliers of referendum voting behaviour (Remain or 60 per cent plus for Leave). There’s therefore a double weighting for strongly Leave seats, which tended for obvious reasons to have high UKIP votes in 2015. The source for constituency referendum voting is Chris Hanretty’s compilation of published local results and his work modelling the others. An allowance has been made where the Greens have stood down or intervened. The initial model had a national baseline of the Conservatives winning by a 15-point margin, which is where a fair few polls were at the time. That would produce a Con gain of 44 from Labour. Allowing for a few gains from SNP in Scotland, and from UKIP in Clacton and possibly a couple from the Lib Dems, this would be a Con gain of around 52 seats for an overall majority of around 120. The way the model works skews the Conservative gains to the North and white working class England. Labour would hold apparently perilous marginals in London such as Ealing Central & Acton and Brentford & Isleworth, but lose some former heartlands. Strikingly, the Tories would win all three seats in Stoke-on-Trent (Labour since 1935) plus Newcastle-under-Lyme (Labour or radical Liberal since 1906) for...
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